Consider the market for interest-based message boards. Many of them sport designs straight out of the Geocities era. The market is fragmented across a variety of small-time, under-funded players. And the biggest message board of them all, Reddit, is lately teetering on the brink of revolution. Meanwhile, Google+ has a photography forum with 1.8 million members. If you’re Google, and you want to create a place for a social network to grow organically — well, web forums can begin to sound a lot like a wedge.